【单选题】
设R和S是集合A上的等价关系，则R∪S的对称性___。
A. 一定成立
B. 一定不成立
C. 不一定成立
D. 不可能成立
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答案
A
解析
暂无解析
相关试题
【单选题】
下列代数系统<S，*>中，哪个是群？___。
A. S={0,1,3,5}，* 是模7加法
B. S=Q（有理数集合），* 是一般乘法
C. S=Z（整数集合），* 是一般减法
D. S={1,3,4,5,9}，* 是模11乘法
【单选题】
具有如下定义的代数系统<G，*>，哪个不构成群？___
A. G={1,10}，* 是模11乘法
B. G={1,3,4,5,9}，* 是模11乘法]
C. G=Q，* 是普通加法
D. G=Q，* 是普通乘法
【单选题】
设Z是整数集合，＋是一般加法，则下述函数中哪一个不是群<Z，＋>的自同态？ ___
A. f(x)=2x
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【单选题】
下面哪个集合关于指定的运算构成环？ ___
A. ，关于数的加法和乘法
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【单选题】
给定下列序列，可构成无向简单图的结点度数序列的是___。
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C. （0，1，3，3，3）
D. （1，3，4，4，5）
【单选题】
设D=<V,E>为有向图，V={a,b,c,d,e,f}，E={<a,b>,<b,c>,<a,d>,<d,e>,<f,e>}是___。
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【单选题】
设|V|>1，D=<V,E>是强连通图，当且仅当___。
A. D中至少有一条通路
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【单选题】
Present-day society is much freer and easier because it emphasizes _________. ___
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【单选题】
Which is the main idea of the last paragraph? ______________ ___
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【单选题】
Permissive parents would ________. ___
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【单选题】
The fact that parents check the contents of the book or the film for their children to read or see shows __________. ___
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【单选题】
Which of the following statements is NOT true?____________ ___
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【单选题】
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【单选题】
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【单选题】
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【单选题】
The tests themselves are by no means free from error..." (Line 1-2.Para.3) means ____________. ___
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【单选题】
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【单选题】
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【单选题】
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【单选题】
The author argues that a teacher's chief concern should be the development of the student's _________. ___
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【单选题】
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【单选题】
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【单选题】
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【单选题】
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【单选题】
What benefit will distance learning program bring to a business? __________ ___
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【单选题】
Good distance learning program have the following characteristic EXCEPT______. ___
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【单选题】
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【单选题】
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